Electric housing device having an adjustable span

ABSTRACT

The invention relates to an electric housing device having an adjustable span, comprising a main body portion, a winding cord, and a first moving part and a second moving part close to the two ends of the main body portion. The main body portion is provided with a driving device, and the bottom of the main body portion is provided with two parallel slide rails which slide along the length direction of the main body portion. The two slide rails extend towards the first moving part and the second moving part respectively and are fixed to the bottoms of the corresponding moving parts. The main body portion and the first moving part, and the main body portion and the second moving part are respectively provided with through grooves corresponding to the two slide rails, each through groove is located on the outside of the corresponding slide rail, each slide rail is slidably provided with a central running pulley, and the top of each central running pulley extends out from the corresponding through groove. The winding cord revolves around the driving device, the main body portion, the first moving part and the second moving part for one circle and winds around the driving device for several circles. The tops of the central running pulleys are fixed to the winding cord. The device is adjustable in terms of span, widely applicable and light in weight.

TECHNICAL FIELD

The present invention relates to an electric housing device, particularly to an electric housing device having an adjustable span.

DESCIPTION OF THE BACKGROUND

Electric housing devices typically are used to install curtains or hang screens, mainly apply to windows, skylights, corridors, entrances or zones and play a role of isolation or shielding. In general, curtains are drawn open or close by remote controller. As the opening or closing is convenient and fast and not liable to damage of the curtains, electronic housing devices are favored by the people. The span of the existing electric housing devices is fixed and not adjustable and is matched with the width of windows or skylights, so during manufacturing of an electric housing device, the width of the window or skylight must be measured in advance, raising use cost and limiting use scope. Further, the motor of an existing electric housing device is installed on one end of the device in general, and drives the device from one end of the device. This motor generally has a large volume and occupies a large space, causing inconvenience in use.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the defects of the prior art, and provide an electric housing device, which is adjustable in terms of span, widely applicable, light in weight and convenient in use.

The present invention provides an electric housing device having an adjustable span, comprising a main body portion, a winding cord, and a first moving part and a second moving part close to the two ends of the main body portion, the main body portion is provided with a driving device, and the bottom of the main body portion is provided with two parallel slide rails which slide along the length direction of the main body portion; the two slide rails extend towards the first moving part and the second moving part respectively and are fixed to the bottoms of the corresponding moving parts; the main body portion and the first moving part, and the main body portion and the second moving part are respectively provided with through grooves corresponding to the two slide rails, and each through groove is located on the outside of the corresponding slide rail; each slide rail is slidably provided with a central running pulley, the top of each central running pulley extends out from the corresponding through groove, and when the central running pulleys slide on the slide rails, the tops of the central running pulleys move along the through grooves; the winding cord revolves around the driving device, the main body portion, the first moving part and the second moving part for one circle and winds around the driving device for several circles; and the tops of the central running pulleys are fixed to the winding cord.

Further, the main body portion is provided with a first positioning piece and a second positioning piece that are diagonally arranged and located on the two sides of the driving device respectively; the first moving part and the second moving part are respectively provided with a third positioning piece and a fourth positioning piece corresponding to the second positioning piece and the first positioning piece; the third positioning piece and the fourth positioning piece are close to the outer end of the first moving part and the outer end of the second moving part respectively; and the winding cord revolves around the driving device, the second positioning piece, the third positioning piece, the first positioning piece and the fourth positioning piece for one circle.

Further, pulley structures are provided at the locations where the main body portion is close to the first moving part and the second moving part respectively, and the winding cord revolves around the driving device, the second positioning piece, the third positioning piece, the pulley structure of the main body portion and the first moving part, the first positioning piece, the fourth positioning piece, and the pulley structure of the main body portion and the second moving part for one circle, and winds around the two pulley structures for one and a half circles respectively.

Further, each pulley structure comprises a frame rack, a movable pulley and a fixed pulley; the frame rack comprises a sliding frame and a fixed frame connected to the sliding frame; the sliding frame is slidably connected to the sliding groove of the main body portion, and the fixed pulley is fixed inside one end of the sliding frame; the fixed frame is fixed to the corresponding moving part, and the movable pulley is arranged inside an end of fixed frame in a movable manner and may slide along the direction of the fixed pulley; and the winding cord winds around the movable pulley and the fixed pulley for one and a half circles.

Further, a support structure corresponding to the sliding frame is provided inside the sliding groove for supporting the sliding frame.

Further, the support structure comprises two support components for respectively supporting the two frame walls of the sliding frame.

Further, a suspension plate is extended from the support structure towards the fixed frame and received in the fixed frame.

Further, the through groove of the main body portion and the first moving part is between the second positioning piece and the third positioning piece and its two ends are close to the second positioning piece and the third positioning piece respectively; the through groove of the main body portion and the second moving part is between the first positioning piece and the fourth positioning piece and its two ends are close to the first positioning piece and the fourth positioning piece respectively.

Further, a number of positioning frameworks are provided on the through groove of the main body portion and the first moving part, and the through groove of the main body portion and the second moving part respectively, and the winding cord passes through the positioning frameworks; and when the central running pulley slides on the slide rail, the top of the central running pulley can move inside a number of the corresponding positioning frameworks.

Further, the positioning frameworks are in a U shape.

Further, the winding cord revolves around the driving device, the second positioning piece, a number of positioning frameworks of the main body portion and the first moving part, the third positioning piece, the pulley structure of the main body portion and the first moving part, the first positioning piece, a number of positioning frameworks of the main body portion and the second moving part, the fourth positioning piece, and the pulley structure of the main body portion and the second moving part for one circle.

Further, the driving device comprises a gearbox, a motor connected to the gearbox and a roller connected to the motor; the winding cord winds around the roller for a number of circles; the gearbox is used to control the rotating direction of the motor, the motor is used to control the rotating direction of the roller, and the roller is used to drive the winding cord to move.

Further, the gearbox comprises a circuit board, the circuit board comprises a microprocessor and a motion control sensor connected to the microprocessor, and the motion control sensor is connected to a remote controller.

Further, the main body portion comprises a middle part and side parts formed at the two ends of the middle part, the driving device is mounted in the middle position of the middle part, the first moving part and the second moving part are respectively close to the outer ends of the corresponding side parts; the first positioning piece and the second positioning piece are provided at the two opposite angles of the middle part.

Further, the corresponding sliding grooves are arranged on the two side parts respectively.

Further, the pulley structure of the main body portion and the first moving part, and the pulley structure of the main body portion and the second moving part are respectively arranged on the inner sides of the corresponding slide rails.

Compared with the prior art, the present invention has the following beneficial effects: the first moving part and the second moving part of the electric housing device provided in the present invention may be drawn apart along two slide rails from the two sides of the main body portion, so the span of this device is adjustable. The present invention may be used to install curtains or display units, such as projection screens or advertising banners and is widely used, thereby reducing use cost. When it is used to install curtains, it may be applied to windows, skylights, entrances, corridors or zones in various widths and play a role of isolation or shielding, and when it is used to install display units, it may be applied to playrooms or exhibition rooms in various widths, and play a role of displaying dynamic or static patterns. Further, as the driving device is installed in the main body portion and occupies a small space, this device is lighter and can be used in a more convenient manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of an electric housing device having an adjustable span provided in an embodiment of the present invention.

FIG. 2 is a schematic plan of the bottom of the electric housing device in FIG. 1.

FIG. 3 is a structural schematic view indicating the first moving part and the second moving part of the electric housing device in FIG. 1 are outwardly drawn apart to form a maximum span.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be further described by referring to the accompanying drawings and embodiments.

As shown in FIG. 1 and FIG. 2, the present invention provides an electric housing device having an adjustable span, comprising a main body portion 1, a winding cord 3, and a first moving part 2 a and a second moving part 2 b close to the two ends of the main body portion 1. The first moving part 2 a is located on the left of the main body portion 1, and the second moving part 2 b is located on the right of the main body portion 1.

The main body portion 1 is provided with a driving device 4, and the bottom of the main body portion 1 is provided with two parallel slide rails 6 which slide along the length direction of the main body portion 1. The two slide rails 6 extend towards the first moving part 2 a and the second moving part 2 b respectively and are fixed to the bottoms of the corresponding moving parts. Specifically, each slide rail 6 has a sliding end 6 a and a fixed end 6 b. The sliding end 6 a is connected to the bottom of the main body portion 1 in a slidable manner, and the top of the fixed end 6 b is fixed to the corresponding moving part. The first moving part 2 a may be drawn apart by a certain distance from the left of the main body portion 1 under the action of the corresponding slide rail 6, and the second moving part 2 b may be drawn apart by a certain distance from the right of the main body portion 1 under the action of the corresponding slide rail 6. The main body portion 1 and the first moving part 2 a, and the main body portion 1 and the second moving part 2 b are respectively provided with through grooves 10 corresponding to the two slide rails 6, and each through groove 10 is located on the outside of the corresponding slide rail 6. Each slide rail 6 is slidably provided with a central running pulley 7, the top of each central running pulley 7 extends out from the corresponding through groove 10, and when the central running pulleys 7 slide on the slide rails 6, the tops of the central running pulleys 7 move along the through grooves 10. The winding cord 3 revolves around the driving device 4, the main body portion 1, the first moving part 2 a and the second moving part 2 b for one circle and winds around the driving device 4 for several circles. The tops of the central running pulleys 7 are fixed to the winding cord 3. The driving device 4 is used to drive the winding cord 3 to move. When the driving device 4 drives the winding cord 3 to move to the left of the main body portion 1 or to the right of the main body portion 1, the winding cord 3 will drive the two central running pulleys 7 to slide towards each other or away from each other. As shown in FIG. 2, in this embodiment, the side of each slide rail 6 adjacent to the other slide rail 6 is defined as an inner side, and the other side of the slide rail 6 is defined as an outer side. The side of a through groove 10 adjacent to a slide rail 6 is defined as an inner side of the through groove, and the other side of the through groove 10 is defined as an outer side. The ends of the first moving part 2 a and the second moving part 2 b that are close to the two ends of the main body portion 1 respectively are defined as inner ends, and the ends that are farther from the two ends of the main body portion 1 are defined as outer ends.

Through this structural design, the first moving part 2 a and the second moving part 2 b may be drawn apart outwardly along the two slide rails 6 from the two sides of the main body portion 1, as shown in FIG. 3, to make the inner end of the first moving part 2 a and the inner end of the second moving part 2 b apart from the two ends of the main body portion 1, thereby the span of this electric housing device may be increased to adapt to multiple occasions with different widths, realize a wide scope of use and make for people's use. The winding cord 3 winds around the driving device 4 for several cycles so that it has enough length when the first moving part 2 a and the second moving part 2 b are drawn apart outwardly. The driving device 4 is mounted to the main body portion 1. Compared with the prior design, it occupies a smaller space and reduces the weight of the whole device.

In this embodiment, the main body portion 1 is provided with a first positioning piece 14 and a second positioning piece 15 that are diagonally arranged and located on the left and right sides of the driving device 4 respectively. The first positioning piece 14 and the first moving part 2 a are on a same side, and the second positioning piece 15 and the second moving part 2 b are on a same side. The first moving part 2 a and the second moving part 2 b are respectively provided with a third positioning piece 16 and a fourth positioning piece 17 corresponding to the second positioning piece 15 and the first positioning piece 14. The third positioning piece 16 and the fourth positioning piece 17 are close to the outer end of the first moving part 2 a and the outer end of the second moving part 2 b respectively. The two through grooves 10 are located between the first positioning piece 14 and the fourth positioning piece 17, and between the second positioning piece 15 and the third positioning piece 16 respectively. The winding cord 3 revolves around the driving device 4, the second positioning piece 15, the third positioning piece 16, the first positioning piece 14 and the fourth positioning piece 17 for one circle to position the trajectory of the winding cord 3.

The first positioning piece 14 and the second positioning piece 15 are components of a same structure, as shown in FIG. 3. Such a component comprises a lower panel 14 a arranged on the main body portion 1, an annular component (not visible in the diagram) arranged on the lower panel 14 a, and an upper panel 14 b arranged on the annular component. The upper panel 14 b and the lower panel 14 a are mounted to the main body portion 1 via fasteners. The winding cord 3 winds around the annular component. The third positioning piece 16 and the fourth positioning piece 17 are components of a same structure. Such a component comprises an annular component 17 a and a panel 17 b formed on the top of the annular component 17 a. The panel 17 b is mounted to the moving part on the corresponding side via fasteners. The winding cord 3 winds around the annular component 17 a. The annular component and the annular component 17 a are components of a same structure, and the connecting line between their centers is parallel with the through groove 10. In this way, the winding cord 3 can drive the central running pulley 7 to slide smoothly, and its sliding track is parallel with the through groove 10.

In this embodiment, the driving device 4 comprises a gearbox 11, a motor connected to the gearbox 11 (not indicated in the diagram) and a roller connected to the motor 5. The gearbox 11 is used to control the rotating direction of the motor, and the motor controls the rotating direction of the roller 5. The rotating directions include clockwise direction and anticlockwise direction. The roller 5 is used to drive the winding cord 3 to move. When the motor controls the roller 5 to rotate anticlockwise, the winding cord 3 moves towards the right side of the main body portion 1, and drives the two central running pulleys 7 to move towards each other. When the motor controls the roller 5 to rotate clockwise, the winding cord 3 moves towards the left side of the main body portion 1 and drives the two central running pulleys 7 to move away from each other.

The gearbox 11 comprises a circuit board, the circuit board comprises a microprocessor and a motion control sensor connected to the microprocessor, and the motion control sensor is connected to a remote controller. The motion control sensor is used to receive the ON/OFF order from the remote controller and send this order to the microprocessor. The microprocessor receives this ON/OFF control order and executes it to control the rotating direction of the motor, thereby controlling the rotating direction of the roller 5 to achieve control of the rotating direction of the winding cord 3, and control of the rotating direction of the two central running pulleys 7.

Pulley structures 8 are provided at the locations where the main body portion 1 is close to the first moving part 2 a and the second moving part 2 b respectively. The pulley structure 8 of the main body portion 1 and the first moving part 2 a, and the pulley structure 8 of the main body portion 1 and the second moving part 2 b are respectively located on the inner sides of the corresponding slide rails 6. The centers of the pulley structures 8 are roughly flush with the center of the main body portion 1. The winding cord 3 revolves around the driving device 4, the second positioning piece 15, the third positioning piece 16, the pulley structure 8 of the main body portion 1 and the first moving part 2 a, the first positioning piece 14, the fourth positioning piece 17, and the pulley structure 8 of the main body portion 1 and the second moving part 2 b for one circle, and winds around the pulley structure 8 of the main body portion 1 and the first moving part 2 a, and the pulley structure 8 of the main body portion 1 and the second moving part 2 b for one and a half circles respectively.

As shown in FIG. 3, a pulley structure 8 comprises a rectangle-like frame rack 18, a movable pulley 19 and a fixed pulley 20. The frame rack 18 comprises a sliding frame 22 and a fixed frame 21 connected to the sliding frame 22. The sliding frame 22 and the fixed frame 21 are formed integrally. The sliding frame 22 and the fixed frame 21 are same U-like structures. The sliding frame 22 is connected to the sliding groove 23 of the main body portion 1 in a slidable manner, and the fixed pulley 20 is fixed to an end of the sliding frame 22. The fixed frame 21 is fixed to a corresponding subpart. The movable pulley 19 is arranged inside an end of the fixed frame 21 in a movable manner and may slide along the direction of the fixed pulley 20. The winding cord 3 winds around the movable pulley 19 and the fixed pulley 20 for one and a half circles. When the first moving part 2 a and the second moving part 2 b are drawn apart outwardly, under the action of the pull, the winding cord 3 will make the movable pulley 19 slide along the direction of the fixed pulley 20, and eventually close to the fixed pulley 20, thereby increasing the length of the winding cord 3 and the winding cycles of the winding cord 3 around the driving device 5 and driving the central running pulley 7 to slide a longer distance.

In this embodiment, a support structure corresponding to the sliding frame 22 is provided inside the sliding groove 23 for supporting the sliding frame. A suspension plate 25 is extended from the support structure towards the fixed frame 21 and received in the fixed frame 21. When the first moving part 2 a and the second moving part 2 b are drawn apart outwardly, the sliding frame 22 slides out from the sliding groove 23 and settled on the suspension plate 25 to separate the pulley structure 8 from the main body portion 1. The suspension plate 25 plays a supporting role to the sliding frame 22. Further, in the process when the first moving part 2 a and the second moving part 2 b are drawn apart and close, the suspension plate 25 also plays a guiding role to the sliding frame 22.

In this embodiment, the support structure comprises two support components 24, which are used to respectively support the two frame walls of the sliding frame 22 and have bevels.

The through groove 10 of the main body portion 1 and the first moving part 2 a is between the second positioning piece 15 and the third positioning piece 16 and its two ends are close to the second positioning piece 15 and the third positioning piece 16 respectively. The through groove 10 between the main body portion 1 and the second moving part 2 b is between the first positioning piece 14 and the fourth positioning piece 17 and its two ends are close to the first positioning piece 14 and the fourth positioning piece 17 respectively. A number of positioning frameworks 9 are provided on the through groove 10 of the main body portion 1 and the first moving part 2 a and the through groove 10 of the main body portion 1 and the second moving part 2 b at intervals. The centers of the positioning frameworks 9 on the through groove 10 of the main body portion 1 and the first moving part 2 a are basically flush with the outer side face of the annular component of the second positioning piece 15, and the outer side face of the annular component 17 a of the third positioning piece 16. The centers of the positioning frameworks 9 on the through groove 10 of the main body portion 1 and the second moving part 2 b are basically flush with the outer side face of the annular component of the first positioning piece 14, and the outer side face of the annular component 17 a of the fourth positioning piece 17. The winding cord 3 passes through the positioning frameworks 9 to assure the trajectory of the winding cord 3 between the second positioning piece 15 and the third positioning piece 16, and between the first positioning piece 14 and the fourth positioning piece 17 is parallel with corresponding through grooves 10 when the winding cord 3 moves. When the central running pulley 7 slides on the slide rail 6, its top may move inside a number of positioning frameworks 9, making for the movement of the central running pulley 7.

In this embodiment, there are 7 positioning frameworks 9 on the through groove 10 of the main body portion 1 and the first moving part 2 a. They are in various sizes. Two of them are on the main body portion 1 and are connected with a baffle on the inner side of the through groove 10. The remaining five positioning frameworks 9 are located on the first moving part 2 a and one of them is at the location where the main body portion 1 is close to the first moving part 2 a and each two of the rest four positioning frameworks 9 are connected with a baffle on the inner side of the through groove 10. Similarly, there are seven positioning frameworks 9 on the through groove 10 of the main body portion 1 and the second moving part 2 b. They are in various sizes. Two of them are on the main body portion 1 and are connected with a baffle on the inner side of the through groove 10. The remaining five positioning frameworks 9 are located on the second moving part 2 b and one of them is at the location where the main body portion 1 is close to the second moving part 2 b and each two of the rest four positioning frameworks 9 are connected with a baffle on the inner side of the through groove 10. The positioning frameworks 9 are in a U shape to make for the passage of the winding cord 3 and the movement on the central running pulley 7.

In this embodiment, the main body portion 1 is further provided with a cross positioning piece 30, which is close to the driving device 4 and between the driving device 4 and the first positioning piece 14 and corresponds to the pulley structure 8 of the main body portion 1 and the second moving part 2 b. The center of the cross positioning piece 30 and the center of the pulley structure 8 of the main body portion 1 and the second moving part 2 b are basically on a straight line so that the winding cord 3 can easily wind around the driving device 4.

The winding cord 3 revolves around the driving device 4, the second positioning piece 15, a number of positioning frameworks 9 of the main body portion 1 and the first moving part 2 a, the third positioning piece 16, the pulley structure 8 of the main body portion 1 and the first moving part 2 a, the first positioning piece 14, a number of positioning frameworks 9 of the main body portion 1 and the second moving part 2 b, the fourth positioning piece 17, the pulley structure 8 of the main body portion 1 and the second moving part 2 b, and the cross positioning piece 30 for one circle. It is the trajectory of the winding cord 3.

Preferably, a positioning framework 9 is provided between the third positioning piece 16 and the pulley structure 8 of the main body portion 1 and the first moving part 2 a, and between the fourth positioning piece 17 and the pulley structure 8 of the main body portion 1 and the second moving part 2 b respectively. The centers of the two positioning frameworks 9 are basically flush with the outer side face of the annular component 17 a of the third positioning piece 16 and the outer side face of the annular component 17 a of the fourth positioning piece 17 to assure the trajectory of the winding cord 3 between the third positioning piece 16 and the pulley structure 8 of the main body portion 1 and the first moving part 2 a and the trajectory of the winding cord 3 between the fourth positioning piece 17 and the pulley structure 8 of the main body portion 1 and the second moving part 2 b are parallel with the corresponding through grooves 10 respectively.

As shown in FIG. 3, in this embodiment, the main body portion 1 comprises a middle part 12 and side parts 13 a and 13 b formed at the two ends of the middle part 12. Preferably, the middle part 12 and the side parts 13 a and 13 b at its two ends are formed integrally. The driving device 4 is mounted in the middle of the middle part 12. The first moving part 2 a and the second moving part 2 b are respectively close to the outer ends of the corresponding side parts. The foregoing corresponding sliding grooves 23 are provided on the two side parts 13 a and 13 b respectively. The foregoing first positioning piece 14 and second positioning piece 15 are provided on the bottom left and bottom right of the middle part 12 respectively. It may be understood that the foregoing first positioning piece 14 and second positioning piece 15 may be provided on the top left and top right of the middle part 12 respectively, too.

The electric housing device of the present invention may be used to install curtains, such as cloth curtains and plastic curtains and is mainly applied on the occasions such as windows, skylights, gateways and corridors, playing a role of isolation or shielding. It may also be used to install display units, such as projection screens and advertising banners and is mainly applied on the occasions such as playrooms, exhibition rooms and performance halls, playing a role of displaying static or dynamic patterns.

When the present invention is used to install a curtain, firstly the two ends of the curtain are installed to two central running pulleys 7. Alternatively, a plurality of pulleys may be installed between the two ends of the curtain and on corresponding slide rails 6 so that the curtain can be drawn open or close in a better way. When the curtain needs to be drawn open, the motor controls the roller 5 to rotate clockwise, the roller drives the winding cord 3 to move to the left of the main body portion 1, and the winding cord 3 drives the two central running pulleys 7 to move away from each other, thereby drawing open the curtain, playing a role of isolation or shielding. When the curtain needs to be drawn close, the motor controls the roller 5 to rotate anticlockwise, the roller drives the winding cord 3 to move to the right of the main body portion 1, and the winding cord 3 drives the two central running pulleys 7 to move towards each other, thereby drawing the curtain close. When the span needs to be increased, the first moving part 2 a and the second moving part 2 b may be drawn apart outwardly from the left and right of the main body portion 1 before carrying out the foregoing steps, i.e., drawing open or close the curtain.

Likewise, when the present invention is used to install a display unit, firstly the two ends of the display unit are installed to two central running pulleys 7. Alternatively, a plurality of pulleys may be installed between the two ends of the display unit and on corresponding slide rails 6 so that the display unit can be drawn open or close in a better way. When the display unit needs to be drawn open, the motor controls the roller 5 to rotate clockwise, the roller drives the winding cord 3 to move to the left of the main body portion 1, and the winding cord 3 drives the two central running pulleys 7 to move away from each other, thereby drawing open the display unit, playing a role of displaying static or dynamic patterns. When the display unit needs to be drawn close, the motor controls the roller 5 to rotate anticlockwise, the roller drives the winding cord 3 to move to the right of the main body portion 1, and the winding cord 3 drives the two central running pulleys 7 to move towards each other, thereby drawing the display unit close. When the span needs to be increased, the first moving part 2 a and the second moving part 2 b may be drawn apart outwardly from the left and right of the main body portion 1 before carrying out the foregoing steps, i.e., drawing open or close the display unit.

The foregoing embodiments only represent the preferred embodiments of the present invention. Their descriptions are concrete and detailed, but they shall not be therefore understood as limitations to the scope of the present invention patent. It shall be noted that for those skilled in the art, various changes and modifications may be made to the embodiments without departing from the spirit of the present invention, such as: combinations of different features of the embodiments. All these shall be in the protective scope of the present invention. 

1. An electric housing device having an adjustable span, comprising a main body portion, a winding cord, and a first moving part and a second moving part close to the two ends of the main body portion, wherein: the main body portion is provided with a driving device, and the bottom of the main body portion is provided with two parallel slide rails which slide along the length direction of the main body portion; the two slide rails extend towards the first moving part and the second moving part respectively and are fixed to the bottoms of the corresponding moving parts; the main body portion and the first moving part, and the main body portion and the second moving part are respectively provided with through grooves corresponding to the two slide rails, and each through groove is located on the outside of the corresponding slide rail; each slide rail is slidably provided with a central running pulley, the top of each central running pulley extends out from the corresponding through groove, and when the central running pulleys slide on the slide rails, the tops of the central running pulleys move along the through grooves; the winding cord revolves around the driving device, the main body portion, the first moving part and the second moving part for one circle and winds around the driving device for several circles; and the tops of the central running pulleys are fixed to the winding cord.
 2. The electric housing device having an adjustable span according to claim 1, wherein: the main body portion is provided with a first positioning piece and a second positioning piece that are diagonally arranged and located on the two sides of the driving device respectively; the first moving part and the second moving part are respectively provided with a third positioning piece and a fourth positioning piece corresponding to the second positioning piece and the first positioning piece; the third positioning piece and the fourth positioning piece are close to the outer end of the first moving part and the outer end of the second moving part respectively; and the winding cord revolves around the driving device, the second positioning piece, the third positioning piece, the first positioning piece and the fourth positioning piece for one circle.
 3. The electric housing device having an adjustable span according to claim 2, wherein: pulley structures are provided at the locations where the main body portion is close to the first moving part and the second moving part respectively, and the winding cord revolves around the driving device, the second positioning piece, the third positioning piece, the pulley structure of the main body portion and the first moving part, the first positioning piece, the fourth positioning piece, and the pulley structure of the main body portion and the second moving part for one circle, and winds around the two pulley structures for one and a half circles respectively.
 4. The electric housing device having an adjustable span according to claim 3, wherein: each pulley structure comprises a frame rack, a movable pulley and a fixed pulley; the frame rack comprises a sliding frame and a fixed frame connected to the sliding frame; the sliding frame is slidably connected to the sliding groove of the main body portion, and the fixed pulley is fixed inside one end of the sliding frame; the fixed frame is fixed to the corresponding moving part, and the movable pulley is arranged inside an end of the fixed frame in a movable manner and may slide along the direction of the fixed pulley; and the winding cord winds around the movable pulley and the fixed pulley for one and a half circles.
 5. The electric housing device having an adjustable span according to claim 4, wherein: a support structure corresponding to the sliding frame is provided inside the sliding groove for supporting the sliding frame.
 6. The electric housing device having an adjustable span according to claim 5, wherein: the support structure comprises two support components for respectively supporting the two frame walls of the sliding frame.
 7. The electric housing device having an adjustable span according to claim 5, wherein: a suspension plate is extended from the support structure towards the fixed frame and received in the fixed frame.
 8. The electric housing device having an adjustable span according to claim 2, wherein: the through groove of the main body portion and the first moving part is between the second positioning piece and the third positioning piece and its two ends are close to the second positioning piece and the third positioning piece respectively; and the through groove of the main body portion and the second moving part is between the first positioning piece and the fourth positioning piece and its two ends are close to the first positioning piece and the fourth positioning piece respectively
 9. The electric housing device having an adjustable span according to claim 8, wherein: a number of positioning frameworks are provided on the through groove of the main body portion and the first moving part, and the through groove of the main body portion and the second moving part respectively, and the winding cord passes through the positioning frameworks; and when the central running pulley slides on the slide rail, the top of the central running pulley can move inside a number of the corresponding positioning frameworks.
 10. The electric housing device having an adjustable span according to claim 9, wherein: the positioning frameworks are in a U shape.
 11. The electric housing device having an adjustable span according to claim 10, wherein: the winding cord revolves around the driving device, the second positioning piece, a number of positioning frameworks of the main body portion and the first moving part, the third positioning piece, the pulley structure of the main body portion and the first moving part, the first positioning piece, a number of positioning frameworks of the main body portion and the second moving part, the fourth positioning piece, and the pulley structure of the main body portion and the second moving part for one circle.
 12. The electric housing device having an adjustable span according to claim 1, wherein: the driving device comprises a gearbox, a motor connected to the gearbox and a roller connected to the motor; the winding cord winds around the roller for a number of circles; and the gearbox is used to control the rotating direction of the motor, the motor is used to control the rotating direction of the roller, and the roller is used to drive the winding cord to move.
 13. The electric housing device having an adjustable span according to claim 12, wherein: the gearbox comprises a circuit board, the circuit board comprises a microprocessor and a motion control sensor connected to the microprocessor, and the motion control sensor is connected to a remote controller.
 14. The electric housing device having an adjustable span according to claim 4, wherein: the main body portion comprises a middle part and side parts formed at the two ends of the middle part, the driving device is mounted in the middle position of the middle part, the first moving part and the second moving part are respectively close to the outer ends of the corresponding side parts; the first positioning piece and the second positioning piece are provided at the two opposite angles of the middle part.
 15. The electric housing device having an adjustable span according to claim 14, wherein: the corresponding sliding grooves are arranged on the two side parts respectively.
 16. The electric housing device having an adjustable span according to claim 3, wherein: the pulley structure of the main body portion and the first moving part, and the pulley structure of the main body portion and the second moving part are respectively arranged on the inner sides of the corresponding slide rails. 